Quantum backaction evading measurements of a silicon nitride membrane resonator

Abstract

Quantum backaction disturbs the measurement of the position of a mechanical oscillator by introducing additional fluctuations. In a quantum backaction measurement technique, the backaction can be evaded, although at the cost of losing part of the information. In this work, we carry out such a quantum backaction measurement using a large 0.5 mm diameter silicon nitride membrane oscillator with 707 kHz frequency, via a microwave cavity readout. The measurement shows that quantum backaction noise can be evaded in the quadrature measurement of the motion of a large object.

Long-lived Quantum State Storage Based on Coherent Mechanical Excitations

“…Finally, the metallized SiN film will form a mechanical parallel-plate capacitor with the bottom rattlesnake microwave coupler. Compared with the traditional process of first metallizing the front side of the silicon nitride film and then flip-chip packaging [57][58][59][60][61][62][63][64], the dielectric of the mechanical capacitor in this work additionally contains silicon nitride, and the cleanliness of the front side of the film is better guaranteed. Therefore, the vacuum gap (mechanical capacitance) can be as small (large) as possible, to improve the optical force coupling strength.…”

“…Meanwhile, silicon nitride (SiN) membrane resonators have been optomechanically coupled to optical [46][47][48][49][50][51][52][53][54][55][56] or microwave cavities [57][58][59][60][61][62][63][64][65][66][67]. Rational exploitation of the spatial distribution of mechanical modes enables simultaneous coupling of the SiN membrane resonator to both superconducting microwave and optical cavity resonators [68,69].…”

“…Rational exploitation of the spatial distribution of mechanical modes enables simultaneous coupling of the SiN membrane resonator to both superconducting microwave and optical cavity resonators [68,69]. Based on microwave field backaction, millimeter-sized SiN membrane resonators have reached their ground-state [61][62][63]. Siliconnitride (SiN) membranes with high stress have a mechanical mode quality factor (Q) in excess of 10 7 , measured in the cryostat [57][58][59][60][61].…”

“…Based on microwave field backaction, millimeter-sized SiN membrane resonators have reached their ground-state [61][62][63]. Siliconnitride (SiN) membranes with high stress have a mechanical mode quality factor (Q) in excess of 10 7 , measured in the cryostat [57][58][59][60][61]. On the other hand, by incorporating phononic bandgap engineering with a SiN membrane [63], the Q-value of the mechanical modes can be further improved in excess of 10 9 .…”